good morning everyone I'm Pro kuku and I'm going  to be doing a presentation on cable ampacity and  

to begin the process I guess it's fair to say  that cable ampacity is really conservation of  

thermal limits like any other device that  thermal determines how much current you  

can put in that device cables are no exceptions  except the conditions are not determined solely  

by manufacturers or by tables we have to do a lot  of work to determine the actual capacities or the  

approximate ampacity that we can put in the cable  based on the cable construction and the layers of  

insulation and and like armor or sheet and so  on the way the location of installation and the  

weight is installed ambient temperature group  in effect the other thermal sources that are  

in vicinity of the cables and of course we're  not just talking about the fundamental convey  

the harmonics would have different temperature  rise in the cable so how do we go about doing  

this the methods are I guess we can say there are  three methods essentially one is actual thermal  

calculations and that's one of the methods  that we're going to go through one is based  

on manufacturer base ampacity and correction  factors and the third method is I'm patty tabled  

by a standard and we'll cover all three of them  during this process the methods that are presented  

in a tab are available in eat AB are listed here  near my graph and is e60 287 those two methods are  

based on thermal analysis then we have I Triple  E 399 IC EA p 54 440 NEC VSS tantor 76 71 and I  

see six zero three six four and I'd like to cover  all of these in half and off so let's see how fast  

we can cover them on the thermal calculation  we have both methods are for underground dark  

banks and direct buried and that is I'm going to  switch the e tap actually right now and bring up  

a dark Bank and for those of you who have not  worked with the dark Bank is it can be in any  

shape or any format that you like to have it I am  moving this cable over and in this cable cable to  

that you see right here is actually a cable in  the one-line diagram it's the same cable if I  

double-click on it you're going to see the same  editor that you double click on a cable from the  

one-line diagram the loading page determines how  much current is flowing through this cable and  

you did you also can select the actual loading of  the cable from from the operating current which  

can also be from that comes from like load  flow or it can be from actual measurements  

in the field from real-time data full load am  from equipment this cable is speed in a switch  

gear and amp rating of the switch gear is 225  so you can say say to that or you can use your  

own and pass it as you like defined user-defined  so if I say for example hundred twenty amps that  

would be useful for the cable sizing of the for  this cable the just to show you this cable I can  

delete it from here go to the Mon line diagram and  I can actually drag and drop this cable from here

I have to be in edit mode I can drop  the drag and drop this cable from here

I'm trying to drag and drop it here we go and  so you can see the same cable that it's exist  

in the bond line diagram is placed right here  now here we can on there from the study case  

I'm waiting for the okay from the silicates  you can see you can select new my graph or  

IEC six year old 287 and the process here I  can do temperature analysis and as soon as I  

do temperature and all set I can look at the  temperature of the cables and as you can see  

I can have extra external heat sources so for  example if I move the external heat source down  

here and do the cable and do the temperature now  says and you can see lot of cables are over the  

limit now over 90 degrees limit that set right  here so this is essentially you can do both both  

methods for analysis of the I guess I'm done  with with the terminal calculations the layers  

the cape of layers in 7.1 we have increased a lot  of cable layers in the system so it's a lot more  

comprehensive as the type of cables we can handle  for both of these methods for thermal analysis so  

I guess for underground cables you can say this  is the most comprehensive method of doing it if  

I go to the I see a 440 which is really for  cable trays only this method is not really  

a table format although it when you look at the  standard it looks like a table format but is the  

semi thermal calculation you don't have it base  ampacity to calculate the related ampacity all  

the data that pass is actually calculated by this  method for this method if I go to eat up again

if I take the same cable to now I'm going to  I'm not going to use thermal analysis I can go  

right here and select the standard here on the  page ampacity select the I see a 440 and here  

the only option you have is type is above ground  cable trays I can put the height let's say this is  

6 inch height the width is 18 inches and let's  say is 30% feel and as soon as I put this the  

program calculates 453 amps as the current that I  can put in this 750 KC meal cable and you can see  

that there is no reference to any base ampacity  for this cable so this is I see a 54 for 40 and  

you can still have different type of trays and  so on we also have additional leading factors  

because of the fire protection you can have  fire coating fire stop and fire wraps so if  

I go for example fire coating I can select from  the library we only have plain master for fire  

coding and if I put them on each fire coating on  there you can see the related ampacity drop to  

390 amps automatically you can also have fire  wraps additional fire protection or fire stop  

when you going through a wall and by doing by  doing that the delay that I pass T goes down  

as you as you do so so this is the concept on  I guess you can say that method is I see a is  

semi thermal now the rest of the methods that we  have in E cap or the standards are really concept  

of de-rating factors you take the base ampacity  and multiplying it by JD factor and you get the  

related ampacity the bass ampacity could be  data provided by the by the manufacturer or  

it can be provided by the stand or through  tables and I'll go through those as we move  

on the delayed in factors depending on the  type of installation that you have would be  

from based on ambient temperature and conductor  temperature our standard for any installation of  

course but then depending if you install the  cable above ground or on the ground you have  

affected in factors and we'll go through those  as we go through different methods the first  

method is I Triple E 393 339 which is the brown  book now arabica 4 is going to be published as I